Abstract 121: Effects of Tethering Branches on Limb Flexion-induced Deformations of the Human Femoropopliteal Artery

Abstract

Introduction: High failure rates of femoropopliteal artery (FPA) interventions are commonly attributed to severe mechanical deformations that occur with limb movement. Recent data demonstrate large variability in FPA bending and torsion. We hypothesize that FPA branch tethering significantly influences arterial deformations. Methods: Under fluoroscopic guidance, nitinol markers were endovascularly deployed into 22 limbs of 11 human cadavers. Dilute contrast was injected into the FPA, and thin-section CT images were acquired with the limbs in straight (180°) and acutely bent (60°) postures. Image segmentation and 3D reconstruction were used to measure bending and torsion of the FPA by tracking spatial movement of the artery and markers. FPA bends were measured as radii of inscribed spheres, while torsion was calculated by measuring the angle of twist between each pair of consecutive markers in the straight and bent leg configurations. FPA branches were mapped and Pearson correlation r was used to assess whether bending and torsion values correlated with the distance to the nearest branch. Results: At the adductor hiatus the FPA demonstrated a bending radius of 3.43±9.14 mm with 15.03±9.95 °/cm twist, while below the knee the most acute bending radius was 2.21±7.03 mm and the maximum twist was 32.03±10.68 °/cm. Bending and torsion below the knee were more severe than at the adductor hiatus (p<0.01). On average, large branches were observed 6.82± 8.26 mm in proximity to the bend and 5.29± 5.16 mm to the twist in the adductor hiatus and 7.96± 6.52 mm and 6.31± 6.06 mm to the bend and twist below the knee. There was no correlation ( r =-0.22, p=0.32) between bending and branch proximity at the adductor hiatus or in the below the knee arterial segments ( r =-0.11, p=0.30). Similarly, no correlation was observed between twist and branch proximity ( r =0.02, p=0.91 at the adductor hiatus; r =-0.02, p=0.87 below the knee). Conclusions: Limb flexion-induced deformations of the FPA demonstrate severe bending and torsion at the adductor hiatus and below the knee; however, neither bending nor torsion appear to be affected by the proximity of the FPA branches. These data suggest that tethering branches have minimal effect on limb flexion-induced bending and torsion of the FPA.